Here you will find a selction of papers surrounding PRT and associated subjects, all written by the team of engineers and academics at Ultra Global.

Maximization of PRT Station Capacity, TRB 2011, M Lowson, J Hammersley.

ABSTRACT: Approaches to maximize the throughput of PRT stations under peak demand conditions are examined.  Stations must be designed consistent with the limitations of the guideways they serve.  It is shown that simple algebraic models can provide key insights into the design issues and limitations.  The fundamental design requirement is to minimize the overall berth cycle time, including:  door opening, passenger load or unload, door close time, trip initiation, and vehicle  resupply.  http://amonline.trb.org/12k2fd/1 (Anyone can read this paper 1 page at a time, or, if not a TRB 2011 attendee, anyone can pay $15 to download the PDF)

Sampling for Personal Rapid Transit Empty Vehicle Redistribution, J Lees-Miller, TRB 2011.

ABSTRACT: A Personal Rapid Transit (PRT) system uses compact, computer-guided vehicles running on dedicated guideways to carry individuals or small groups directly between pairs of stations. PRT vehicles operate on demand, when a passenger requests service at his/her origin station. Because the number of trips requested from a station need not equal the number of trips ending there, some vehicles must move empty to balance the flows. The empty vehicle redistribution (EVR) problem is to decide which empty vehicles to move, either reactively, in response to known requests, or proactively, in anticipation of future requests. This paper develops a new algorithm for the EVR problem called Sampling and Voting (SV). http://hdl.handle.net/1983/1760, http://amonline.trb.org/12jihg/1

Proactive Empty Vehicle Redistribution for Personal Rapid Transit and Taxis, J Lees-Miller, RE Wilson. U Bristol 2011.

ABSTRACT: The empty vehicle redistribution (EVR) problem is to decide when and where to move empty vehicles in a Personal Rapid Transit or taxi system. These decisions are made in real time by an EVR algorithm. A reactive EVR algorithm moves empty vehicles only in response to known requests; in contrast, a proactive EVR algorithm moves empty vehicles in anticipation of future requests. This paper describes two new proactive EVR algorithms, called Sampling and Voting (SV) and Dynamic Transportation Problem (DTP), that move empty vehicles proactively based on demand estimates from historical data. It also develops methods for assessing the performance of EVR algorithms absolutely in terms of both throughput and passenger waiting times. In simulation tests, the proposed algorithms provide lower passenger waiting times than other algorithms in the literature, and proactive movement of empty vehicles significantly reduces waiting times, usually with a modest increase in empty vehicle travel. http://hdl.handle.net/1983/1761

Specification of a Communication Based Collision Avoidance System (CBCAS), European Commission – Sixth Framework, CityMobil Deliverable Alan Peters, T Ross-Martin (2011).

ABSTRACT: Vehicle navigation, guidance and control on the Ultra PRT guideway is fully autonomous with vehicles following predetermined speed profiles along centrally dictated routes.   A Central Control System (CCS) is used to manage the entire network and co-ordinate vehicle movements, so as to avoid conflicts.  When operating normally, no collision hazards exist since all vehicle movements are designed to be non-conflicting.  However potential collision hazards can arise due to failures within the system (e.g. vehicle breakdown) or intrusions from outside (for example pedestrians trespassing on the guideway network).  Existing systems (at Heathrow and Morgantown) use collision avoidance systems based on wire loops set in the track surface which detect the position of vehicles.  While these systems are conceptually simple they are costly and are likely to have poor availability, due to the large number of components required.  Moreover their simple fixed configuration gives rise to significant performance limitations and they have no capability to prevent collisions with obstacles other than PRT vehicles.  Due to these reasons it is considered desirable to eliminate the use of such systems if PRT is to achieve its full potential.  Since individual PRT vehicles already possess fully autonomous driving functions, know their speeds, locations and intended paths with high precision, and have radio communications equipment to communicate with the CCS, the function of avoiding collisions between vehicles may be realized (to some extent) at low cost, using pre-existing information and system components to form a Communication Based Collision Avoidance System (CBCAS).  This document sets out the high level requirements for a communication-based collision avoidance system for  use with a PRT system. http://www.citymobil-project.eu/downloadables/Deliverables/D1261%20-%20PU%20-%20CityMobil%20-%20Specification%20of%20a%20Communication%20Based%20Collision.pdf

Theoretical Maximum Capacity as Benchmark for Empty Vehicle Redistribution in Personal Rapid Transit, TRR 2146 / 2010, J Lees-Miller, J Hammersley, RE Wilson.

ABSTRACT: A Personal Rapid Transit (PRT) system uses compact, computer-guided vehicles running on dedicated guideways to carry individuals or small groups directly between pairs of stations. Vehicles move on demand when a passenger requests service at his/her origin station. Because the number of trips requested from a station need not equal the number of trips ending there, some vehicles must run empty to balance the flows. The empty vehicle redistribution (EVR) problem is to decide which empty vehicles to move, and when and where to move them; an EVR algorithm makes these decisions in real time, as passengers arrive and request service. This paper describes a method for finding the theoretical maximum demand (with a given spatial distribution) that a given system could serve with any EVR algorithm, which provides a benchmark against which particular EVR algorithms can be compared. The maximum passenger demand that a particular EVR algorithm can serve can be determined by simulation and then compared to the benchmark. The method is applied to two simple EVR heuristics on two example systems, and the results suggest that this is a useful method for determining the strengths and weaknesses of a variety of EVR heuristics across a range of networks, passenger demands and fleet sizes. http://hdl.handle.net/1983/1759,http://trb.metapress.com/content/n2w2l27366314532/

Analyzing Risks in a Novel Transport System, U. Bristol Conference for Engineering Doctorate in Systems. Alan Peters, T. Ross-Martin(2010).


Ridesharing in Personal Rapid Transit Capacity Planning, ASCE APM Conf 2009, J Lees-Miller, J Hammersley, N Davenport.

ABSTRACT: Passengers on a Personal Rapid Transit (PRT) system usually travel together only by choice, but strangers may choose to share a vehicle when the system is near capacity. By predicting whether and to what extent this ride sharing will occur, PRT planners can better estimate the impact on system capacity and passenger experience. This paper develops a model for ride sharing based on queueing theory and applies it to explain the relationships between vehicle occupancy, passenger queue length and passenger waiting time. The effects of multiple destinations, passengers who are unwilling to share and passengers arriving in preformed parties are considered. A case study is provided to show how the model can be applied to a simple point-to-point system; in this case study a 30% reduction in the size of the vehicle fleet appears possible, while still maintaining a high level of service for passengers. http://hdl.handle.net/1983/1414

Vision-Based Detection of Personal Rapid Transit Guideway, 6th Intl Symposium on Image and Signal Processing and Analysis, Salzburg. Alan Peters, T. Ross-Martin (2009).

ABSTRACT: ULTra is a system of autonomous vehicles operating on a segregated guideway. The existing navigation system requires the use of raised kerbs to assess the vehicles position within the guideway. A vision-based system has the potential to be more flexible by sensing markings on the ground. It could also assist future obstacle detection systems. This paper implements three well known lane detection approaches developed for roads using images from a personal rapid transit (PRT) guideway. The Hough transform technique is found to be the least accurate, the LOIS algorithm is found to have reasonable performance and the RALPH algorithm is found to be the most accurate and robust to noise. Pay to access article: http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5297742

Image Change Detection for a PRT Application, Proc of 16th European Signal Processing Conf., Lausanne Alan Peters, T. Ross-Martin (2008).

ABSTRACT: Automatically identifying objects and people left in the interior of vehicles is highly desirable because human monitoring has high running costs and low efficiency associated with it. The new Ultra PRT) system features many autonomous vehicles and therefore the task is of particular importance. This paper describes two approaches that use changes in the visual image of the interior to predict the likelihood of left objects and remaining people. The first approach is based on identifying structural differences. The second approach uses a shading model method. A variation of the shading model with information from the color channels is also described. The results show that the modified shading model approach gives the best performance.http://www.eurasip.org/Proceedings/Eusipco/Eusipco2008/papers/1569105004.pdf

Major Activity Center PRT Circulator Design: Hacienda Business Park. TRR #2006. S Raney, J Paxson, D Maymudes.

ABSTRACT:The design of a comprehensive mobility system for a suburban San Francisco East Bay Area office park exposes a number of new transit circulator implementation challenges. Original system design perspectives are provided regarding: A) “Horizontal mixed use” and how resident out-commuters will generate more trips than employee in-commuters. B) Line haul transit capacity constraints loom as an obstacle to rapid spread of PRT circulators. C) PRT station placement challenges with office park “superblocks.” D) Design methodology to allocate PRT stations to workers and residents. E) Ideal office park characteristics for PRT alignments. F) Problems with generating too much PRT circulator ridership solved by semi-independent loops. G) Multimodal transit hubs at the edges of the PRT alignment. H) PRT alignment “style choices.” I) The need for folding grocery carts (and other solutions) when the car is left at home. http://www.cities21.org/TRB_PRT_HBP.pdf

PRT for Airport Applications, TRB, January 2005, TRR #1930. M Lowson.

Personal Rapid Transit (PRT) systems offer a series of new opportunities for effective solution of airport related transport problems, both on the landside and airside of the airport. A comparative analysis is offered of the potential advantages and disadvantages of this form of transport for airport applications. The work is illustrated by a case study of the application of the ULTra PRT system to serve passenger and staff car parks at Heathrow. The small scale and flexibility of the ULTra infrastructure allows use of the tunnel sidebores and provides unexpectedly simple integration with the complex central terminal area. Detailed comparisons show a benefit of 60% in trip time and 40% in operating cost over current buses. The study shows that such forms of transport are well matched to land side applications for airports. An outline evaluation of possible benefits for airside operations is also presented. http://www.ultraprt.net/cms/trb05_airports.pdf

Application of New Technology Product Research to New Suburban Commute System Design and Validation, TRR #1927, S Raney.

ABSTRACT: To provide improved alternatives to suburban solo commuting, a technologically-intensive door-to-door mobility service was designed for suburban commutes, with special emphasis on addressing attitudinal/psychological barriers. Literature Review, expert opinion, and GIS journey-to-work analysis influenced the initial conceptualization. Concepts were then iteratively refined through interview research. The final system concept was validated via stated preference surveys employing “gap analysis” to measure the importance of barriers and the effectiveness of proposed solutions. An elaborate “assembly-line” eight-step survey protocol was employed, featuring immersive, virtual-reality based respondent stimuli (information acceleration), full disclosure of psychological barriers, and customized door-to-door commute comparisons. Original contributions include: a) a unique combination of varied product research techniques for the design and demand forecasting of futuristic transportation systems and b) rich anecdotal descriptions of technology worker commute psychology. http://www.cities21.org/NewTechProdMtkng_TRB_111504.pdf

Suburban Silver Bullet: PRT Shuttle and Wireless Commute Assistant with Cellular Location Tracking,TRR #1872 (TRB 2004). S Raney.

ABSTRACT: In a hypothetical Year 2008 scenario, a personal rapid transit (PRT) circulator “shuttle” system and comprehensive door to door “new mobility” service transforms Palo Alto’s major employment center into a transit village of two square miles, complementing and significantly increasing the attractiveness of commuter rail, carpool, vanpool, bicycle, and bus commutes for the center’s 20,000 employees. Of utmost importance, PRT provides faster service than driving alone for the “last mile.” A Transportation Management Association enables a supportive commuting culture. A larger candidate pool accesses the personal “MatchRide” web-based ridematching service, increasing carpool formation.

Proposed are new applications of cellular location tracking technology and Wi-Fi (802.11) enabled handsets to increase the competitiveness of suburban commute alternatives. Cellular phones evolve to become a commuter’s “command center”, an integral part of the workday. The following applications are proposed: A) “TrakRide” to improve the reliability of carpool rendezvous and increase courteous, punctual behavior. B) “NextTrain” to improve the reliability of train-shuttle connections. C) “HomeSafe” to verify that carpools amongst strangers operate safely. D) “QuickCar” to provide five-minute access to cars for centralized car sharing and emergency ride home, using “wireless door key.” E) “SpyKids” to maintain secure custody of children during unaccompanied shuttle trips. F) “NextSpace” to direct commuters to available parking spaces, with wireless access to automated, shared parking lots. A central database, known as “Big Sister,” maintains personal data to support these applications. http://www.cities21.org/PRT_Wireless_TRB_111503_web.pdf